This only makes sense to you because it is based on a caricature, not an actual position any significant group of American's hold.
Right wingers and Republicans are not against immigration. In fact they think it is a healthy and normal thing for the government to allow. There is no call for the hundreds of thousands to millions of immigrants that the government grants citizenship to every year to be restricted or reduced. In reality, many want these efforts and numbers increased, because there are obviously plenty of ineligible non citizens who would be a boon to our nation who can not get in legally. They also champion the nation state system and the sovereign right of a nation to collectively decide who and how many people are allowed to immigrate. Maintaining those powers as a government or supporting them as a citizen is not xenophobia or racism or "anti-immigration" in any way, shape or form.
What they are against is ILLEGAL immigration, which is a no brainer and can only be argued against if you are like Traitorfish and dream of an alternate reality irrelevant to anything, or you are a partisan lefty who artificially dissolves very real distinction between legal and illegal immigration and ignores any support for the former in an attempt to shoehorn accusations of xenophobia/racism/isolationism/buzz word of the week. Or in other words, do what you were doing.
Behold the xenophobia of the US!!! Persons Obtaining Legal Permanent Resident Status:
2007: 1,052,415
2008: 1,107,126
2009: 1,130,818
2010: 1,042,625
Yeah, we really aren't into this whole immigration thing here in America...
I don't mean to call all Republicans "anti-immigrant" or "xenophobes" - for instance, both of the Bushes and Reagan were the very opposite of that. But I have noticed a marked shift away from liberal immigration policy among the Republican party in the last 8 years or so, and I suspect that they are doing this in response to a recent wave of anti-immigrant sentiment. When I use words like "anti-immigrant" or "xenophobic", I'm referring to the people whose votes they appear to be trying to win, not so much Republican politicians themselves.
It would be great if our immigration policy were streamlined, with a guest worker program to allow in people who wish to work in the US, conditional upon passing a background check, filling out appropriate documentation, etc. Permanent resident status could be provided to people who worked in the US for a few years without incident, followed by citizenship a few years after that.
In short, I support a fairly unrestricted immigration policy. People who still manage to run afoul of basic documentation rules should be punished - but the only reasons to ignore immigration law would be to evade taxes or hide a criminal record.
As I understand it, American immigration policy has not functioned in this manner. Instead, it seems that very few visas for unskilled laborers were granted in spite of the fact that such laborers were in high demand. Simultaneously, existing immigration laws were not really enforced, largely because they made no economic sense in the first place.
For some reason, it appears that a significant backlash against immigrants, in particular low-skilled Hispanics, developed throughout the 2000s. As a result, opposition to "illegal immigration" grew dramatically. I am not convinced that the majority of opponents of illegal immigration are actually opposed to the illegality of showing up without the proper paperwork. If they were, they would support some sort of guest worker program in order to actually document everyone properly. But most who express concern about illegal immigration also oppose guest worker programs, despite their obvious economic utility. I cannot make any sense of this.
So I do suspect that anti-immigrant sentiment is behind the sudden appearance, c. 2006, of illegal immigration as a hot-button issue. The passage of draconian laws in places like Arizona and Alabama does not make me think any more favorably about this.
Of course there are good reasons to want immigrants to have appropriate documentation, and I don't think people who insist on proper documents oppose immigration in general. The way to ensure that the immigrants are documented is to allow all people passing certain minimum requirements to be documented immigrants.